The present invention relates to the opening, mixing, and regulation of the flow of textile fibers and, in particular, accomplishing these processing steps by the use of novel feeder constructions.
Hopper feeders have long been used in the textile industry. However, the way such devices have been historically configured and operated has imposed serious limitations on their ability to meet "modern" textile needs.
Textile fibers are normally transported and stored in the form of highly compressed bales. In baled form, the individual fibers are matted and entangled very tightly. Before the fibers can be spun into a yarn, or formed into a non-woven fabric, the hard, high density bales must be literally destroyed and the fibers separated to an almost to a fiber-to-fiber state. The reduction of the bulk density of the bales into progressively smaller and smaller tufts of fibers is commonly referred to as "fiber opening". Naturally, The higher the degree of opening, the greater the volume occupied by a given mass or weight of fibers. A single bale will balloon into a tremendous volume as it is refined into smaller and smaller tufts.
The degree and method of fiber opening is extremely important to the textile industry, because it is well known that fibers cannot be properly cleaned or blended or carded until they have been separated into very small tufts. Likewise, the formation of a fibrous batt, for feeding to a subsequent process, requires the use of very small tufts which have a fairly constant size. With tufts in this condition, they can then be re-assembled in a controlled manner to produce a batt which has a fairly uniform bulk density. This enhances the processing regularity and efficiency.
Although small, distinct tufts are highly desired, great care must be taken in how they are generated. Otherwise, the fibers can be curled, bruised and/or broken which reduces the strength of the yarn or product ultimately formed. Likewise, it is possible to "over-work" the fibers such that fibers, well opened at one point, become twisted and reentangled into small knots or ropes. Fibers in this condition are difficult to process, and form neps which are highly detrimental to the quality of the end-product.
Hopper feeders are frequently used as processing machines for textile fibers, and they generally perform four basic functions: (a) They serve as an intermediate storage reserve, or accumulator, for fibers in transit from one process to another, (b) They serve to open the mass of fibers stored within them, (c) They serve to mix the mass of fibers within the storage chamber, and (d) They serve as a flow regulator for the fibers going to a subsequent process. Naturally, the more highly opened the fibers in the hopper feeder become, the better job of mixing them it can do. Likewise, the flow of fibers can be more precisely regulated whenever they are highly opened into very small tufts.
Prior art hopper feeders have the following principal working elements: (a) a reserve chamber which contains a mass or ball of fibers under process, (b) an advancer element which urges the mass or ball of fibers in the reserve chamber forward in the process, (c) a primary opener element which impales globs of stock and tears them from the mass or ball of fibers in the reserve chamber, (d) a secondary opener element which runs in an opposite direction to the primary opener element and strips a major portion of the impaled globs from it and deposits them back into the reserve chamber for repeated processing, and (e) a doffer element which removes the refined globs or tufts that pass through a fixed gap between the two opener elements and deposits such tufts into a receptacle provided to receive the output from the hopper feeder.
In prior art hopper feeders the primary opener element is usually a spiked lift apron (or needled lattice) comprised of numerous parallel slats which contain a large number of protruding needle pins. However, it is also known that one or more rotatably driven, large diameter drums having pins or large teeth disposed about their surface may also be used to perform this opening and transfer function. Conventional secondary opener elements may also take various forms, for example, reciprocating combs (like Item 22, FIG. 1, of U.S. Pat. No. 3,738,476), rotary kick rolls or coarsely pinned revolving cylinders (like Item 28, FIG. 2, of U.S. Pat. No. 3,889,319), or classical stripper aprons (like Item 44, FIG. 2, of U.S. Pat. No. 3,326,609). Various forms of doffer elements have also been used, for example, sweeping air currents (induced by either fans, or rotating blades or brushes disposed about the surface of revolving cylinders), and rotary kick rolls and reciprocating combs similar to those used as secondary opener elements.
The receptacles associated with prior art hopper feeders may take the form of a weighing pan, which weighs up small batches of stock before dumping it for downstream processing. Such art may be seen for example by reference to U.S. Pat. Nos. 3,071,202; 2,727,279; 3,080,617; 3,073,402; 2,885,741; 2,412,506; and RE No. 25,609. Another form of receptacle is a feed chute for forming a batt to be delivered to either a carding machine or to a blending process and such types of art may be seen, for example, by reference to U.S. Pat. Nos. 3,738,476 and 3,889,319. Yet another form of receptacle used is a pneumatic transport channel which carries the tufts from the doffer to subsequent blending or batt forming operations. Still yet another form of receptacle which has been used is a second hopper feeder disposed immediately downstream of a first hopper feeder, so that the two can work as tandem feeders or in series. One serves as a "breaker" opener and the other serves as a "finisher" opener in order to provide the required degree of fiber opening.
For reasons discussed below, the fiber opening potential of a single prior art hopper feeder is so limited that it is fairly common practice to "pre-open" the stock before feeding it into a hopper feeder for subsequent processing. This is particularly true in the case of critical batt forming applications, such as card feeders. This stock opening inefficiency results in the need for additional processing equipment and the additional costs associated with transporting stock from one processing point to another. The present invention proposes to overcome such disadvantages as these, as well as others described later.
Associated with each of the various type receptacles which have been employed has been some form of quantity sensor which measures the need for stock in the receptacle and feeds back a controlling signal which typically operates the primary opener element in order to control the flow of stock into the receptacle. Quantity sensors with a proven capability to provide such form of control have taken many different forms. For example, various forms of switches and transducers operated by "balanced" beams, slide pans or paddle mechanisms, photo electric transducers and switches, ultra-sonic transducers and switches, air pressure actuated transducers and switches, radiation detectors (electro-magnetic and nuclear), stock thickness measuring transducers, weight load cells, and other means have been successfully used to perform the required measuring function.
The "output" signals from some prior art quantity sensors have been On/Off in nature. Such signals have been used to control, or regulate, the flow of fibers into the receptacle by intermittently starting and stopping the primary opening element. Clearly, during those periods when the primary opening element is stopped, it can do no opening of the fibers. Furthermore, while stopped, this element can do no mixing of the fibers. Since opening and mixing are supremely important, such a waste of precious running-time make these type prior art systems unsuitable to meet the objects of the present invention.
The "output" signals from other type prior art quantity sensors varies in proportion to the amount of mass flowing into (or contained in) the receptacle. These type signals are usually employed to control the mass flow rate from the hopper feeder by continually modulating or varying the speed of the primary opener element. This mode of flow control is usually preferred over the start/stop mode because fewer transients are created in the flow of the process. However, as a practical matter, anytime the primary opening element is run at less than its maximum possible speed, there are fewer numbers of possible stabbings and snatchings of globs from the fibrous mass by the pins carried by the primary opening element. Consequently, the opening and mixing potential for these systems is severely diminished. Therefore, the prior art which regulates the flow of fibers by continuously varying the speed of the primary opening element is also unsuited to meet the objects of the present invention.
Accordingly, an object of the present invention is to provide a fiber feeding apparatus which uses the available running-time to its fullest extent in order to maximize the degree of opening and mixing of the fibers being processed.
Another object of the present invention is to provide a feeding apparatus in which the primary and secondary opening elements can run almost continuously, even though the fibers leaving the feeder are being consumed by an intermittent batching operation or the subsequent process is consuming fibers at a variable rate. The continuous running operation of the primary and secondary opening elements thereby increases the degree of opening and mixing potential.
Another object of the present invention is to provide a feeding apparatus in which the primary and secondary opening elements are operated at a high continuous speed, and do not have to speed up and slow down in order to regulate the flow of fibers through the feeder, providing an increased degree of fiber opening and mixing potential.
Another object of the present invention is to provide a fiber feeding apparatus which employs a variable gap between the primary and secondary opening elements which can be automatically adjusted t regulate the flow of fibers from the feeder despite large variations in the bulk density and other property changes in the fibers contained within the feeder reserve.
Still another object of the present invention is to provide a fiber feeding apparatus which utilizes a variable gap between the primary and secondary opening elements which can be automatically opened or closed or modulated in order to regulate the flow of fibers from the feeder so that it can be used in intermittent short-term batching applications.
Still another object of the present invention is to provide a fiber feeding apparatus which is particularly well suited for the processing of small production lots, as well as large production runs, in that a single feeder can be used to perform both the "pre-opening" and "normal run opening" functions without the need to either transfer or reload the fibers.
Yet another object of the present invention is to provide a fiber feeding apparatus which, for a given degree of fiber opening and mixing, can process a higher amount of fiber per unit time thereby reducing the amount of machinery needed, consuming less energy, and minimizing the need for expensive floor space.